The loudness of the audio output from a television receiver often changes from program to commercial on a given channel, from program to program on a given channel, and from channel to channel. Additionally, many television programs and most motion pictures intentionally vary loudness from scene to scene to simulate how the sounds would be experienced in real life. For example, a gun shot or a cheering crowd at a football game are louder than two people having a face-to-face conversation in a room.
However, such real life loudness variations, while having some value in a movie theater, are often a source of annoyance when viewing television at relatively close range in a relatively confined area. In response, some television manufacturers have incorporated automatic volume leveling (AVL) circuitry in their televisions. Such AVL circuits are similar to analog leveling circuitry found in various audio products such as tape recorders. While these analog AVL circuits provide some relief from loudness variations, they generally suffer from having a limited volume hold time for quiet passages, slow attack and decay (release) times constants, and the additional cost of the AVL circuitry.
Accordingly, it would be advantageous to provide an automatic audio leveling apparatus and method that would provide infinite hold time for quiet passages, fast and precise attack and decay times, and eliminate the need for additional circuitry.